This invention relates to a cold cylinder assembly for use in a cryogenic refrigerator of the type described in the U.S. Pat. to Vuilleumier, No. 1,275,507.
In prior art, Vuilleumier cycle two stage cryogenic refrigerators, the heat load is absorbed by the gas in an annular heat exchanger formed between the cold cylinder and the cold displacer. In these devices, the gas to the second stage passes through the first stage and requires two right angle turns of the gas adjacent the first stage expansion volume. The radial clearance in the annulus is small, for example, 0.005 inch. The small flow area with the two right angle bends causes a pressure loss. There is also a lower thermal efficiency due to the presence of stagnant gas pockets.